Electronic code translation



A118. 2, 1966 A. T. STARR 3,264,638

ELECTRONIC CODE TRANSLATION Filed Oct. 1, 1963 2 Sheets-Sheet 1 a5 2/ 2P j j ,9" II/ FIG. IA

INVENTOR. ARTHUR T. STARR J%%Q&

A TTORNE Y Aug. 2, 1966 A. T. STARR 3,264,638

ELECTRONIC CODE TRANSLATION Filed Oct. 1, 1963 2 Sheets-Sheet 2 l c-$ -R 9009 hi 'H R 1 I ER 00*? I 2 4R I l l I T FIG. 5 1.9T 2/ ELL Bl STABLE INVENTOR. ARTHUR T. STARR i m k A 7' TOR/VEV United States Patent 3,264,638 ELECTRONKI CODE TRANSLATION Arthur T. Starr, New Barnct, England, assignor to Rank Precision Industries Limited, London, England, a corporation of Great Britain Filed Oct. 1, 1963, Ser. No. 312,901 10 Claims. (Cl. 340347) This invention is concerned with improvements in or relating to electronic code translators for translating information in the form of a sequence of coded characters from an input code to an output code, and is concerned especially, but not exclusively, with an electronic code translator for translating information in the form of a sequence of characters from a repertoire of 64 characters from an input code comprising six binary digits to an output code comprising up to thirty-five binary digits to control the control element of a character generation and display tube.

It has been proposed to solve the problem of translating information from one code to another by using code translators comprising diodes, transistors, ferrite cores, resistors, and other circuit elements. These code translators are expensive and lacking in efiiciency especially so in the case where the output code has a relatively large number of digits. It is an object of the present invention to overcome these drawbacks.

According to one aspect of the present invention there is provided an electronic code translator for tnanslating information in the form of a sequence of coded characters from an input code to an output code, comprising a cathode ray tube wherein a plurality of electrically responsive target members, each corresponding to a character and associated with output code members, are arranged to be struck seriatirn by an electron beam to generate appropriate output signals in terms of said output code in response to being struck by said electron beam.

According to another aspect of the present invention, there is provided a method of translating information in the form of a sequence of coded characters, represented by electric input signals arranged according to an input code, into electric signals arranged according to an output code, comprising the steps of directing an electron beam of a cathode ray tube under the control of said input signals seri-atim on to a plurality of electrically responsive target members, each of said target members corresponding to a character and associated with output code members, to obtain corresponding electric output signals according to said output code from said cathode gay tube when a target member is struck by said electron earn.

Embodiments of an electronic code translator according to the present invention will now be particularly described hereinafter by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a sectional elevation, in diagrammatic form, of a code translator tube;

FIGURE 1A is a diagrammatic representation of the target of the tube shown in FIGURE 1;

FIGURE 2 is a circuit diagram illustrating the behaviour of the tube under certain conditions;

FIGURE 3 is a diagrammatic representation of a circuit arrangement for limiting the voltage on certain elements of the tube;

FIGURE 4 is a fragmentary diagrammatic representation of a modification of the tube shown in FIGURES 1 and 2;

FIGURE 5 is a diagrammatic representation of circuit arrangements for the deflection system of the tube shown in FIGURES 1 and 2, and

See

FIGURE 6 is a further circuit arrangement, in block diagram form for the operation of the tube in conjunction with a S-unit code.

Referring to FIGURE 1 of the drawings, a cathode ray tube, generally indicated by the reference numeral 11, having an evacuated envelope 12, is provided with a normal cathode and electron gun 13 to produce an electron beam 14. A deflection system, comprising horizontal deflection plates 15 and vertical deflection plates 16, and focusing means such as anode cylinder 22, is controlled by electric input signals applied to terminals 17 and 18 according to the digits of a six-bit input code, and deflects the beam 14 into one of 64 open-ended target members in the form of boxes 19 of a target 20. Each of these boxes 19 corresponds to a character of the repertoire. The way the deflection voltages are obtained depends upon the nature of the input code, and examples of such ways will be described hereinafter. Into each box 19 are inserted output code members in the form of appropriate digit wires 21, in the way illustrated in FIGURE 1 and FIGURE 1A.

The operation of the code translator tube is as follows. Let the cathode 13 be at a potential V, and let the digit wires 21 at the output have a self-capacitance C and be connected to earth via resistance R, as shown diagrammatically in FIGURE 2. If at any instant the potential of the wire 21 is v, where v is a fraction of V, the beam current i per wire remains substantially constant. The wire 21 charges up toward the potential V according to the law v=-Ri(1e" which for the early part of the rise is v=it/ C. When the beam 14 is removed, the potential of the Wire 21 moves towards zero with a time-constant CR. For example, if the capacitance C is 50 pf. and the potential is to rise 30V in 1 microsecond, i=1.5 ma. The total beam current must be adequate to charge up most of the output digit wires 21 in a box 19, so that a total beam current of 50 ma, is required to give a 30V potential in 1 microsecond. If the rise time is 5 microseconds, the beam current need be only 10 ma. It is convenient to have a decay time of 1 microsecond, in which case R=20Kfl.

The total beam current is shared by all the digit wires 21 in a box 19, so that the rate of rise of wire potential depends on the number of digit wires 21 in any particular box 19. It is desirable to limit the voltage on each wire 21, and this is achievable by means of the circuit shown in FIGURE 3, in which a diode 23 is provided for each output digit wire 21. Each diode 23 is connected to a source of negative potential 24 which is equal to the limiting value desired. When a digit wire 21 attains a potential exceeding that limiting value, an equalising current flows through the diode 23 to clamp, as it is known in the art, the potential of the digit wire 21 at the desired value.

Unless specifically arranged otherwise, the actual box 19 will collect a large part of the total beam 14. The proportion of the beam current collected by the digit wires 21 will be increased by placing a moderately high negative voltage on the boxes 19. Thus, if the cathode 13 is at -l00 v. and the desired digit wire potential is -30 v., the box potential can be maintained at for example v., and this will ensure that the electrons are deflected from the box 19 to the wires 21.

If the box potential is maintained at some potential below that of the cathode 13, then an alternative method is available for limiting the charging potential of the digit wires 21. In this method a grid 25, see FIGURE 4, is placed in front of the boxes 19, and its potential is held at the limiting value required for the digit wires 21. Should a digit wire 21 be charged more than for example 30 volts negative, subsequent approaching electrons will 3 be deflected back to the grid 25. This method avoids the necessity of using the diodes 23 of FIGURE 3.

Turning now to the provision of a suitable deflection system for the beam 14, a preferred system is one in which the deflection system 15, 16 is normal, and the deflection voltages are obtained from six input digits in the way illustrated in FIGURE 5. Any triplets of input signals are added in the adding circuit shown on the left, with an arbitrary binary weighting, to give a voltage for the X deflection; the other three signals are added in the adding circuit shown on the right, and determine the Y voltage. Thus if the input code is 110010, representing the letter T, for example, the X voltage at the terminal 17 has 6 units corresponding to 110 in the binary scale, and the Y voltage at the terminal 18 has 2 units, corresponding to 010 in the binary scale. The beam will then fall into the box in the 6th column and the 2d row. The output wires 21 indicated in FIGURE 1A by the reference numbered 26 for the appropriate symbol of the output code are led into this box 26.

The choice of the triplets can be made so that neighbouring boxes can have as many common wires as possible.

In teleprinters there is a S-unit code, and the elements can be used for the digits 2 to 6 in FIGURE 5. Digit 1 of FIGURE has to be produced from the case signal or the figures-letters signals, in the way shown in FIG- URE 6. The S-unit code input enters a comparator circuit, which gives an output signal when the input is figures. This output sets the bistable to give a steady signal for unit 1. When the letters signal is received, the comparator circuit gives a signal to reset the bistable, to give a zero signal for unit 1.

In order to prevent the beam 14 from entering more than one box 19, a grid 30 of relatively thick wires, see FIGURE 4, is provided in front of the target member 20 in register with the partitions of the target member 20 and in front of the partitions. If this grid 30 of wires is held at a relatively high negative potential, the beam 14 will be switched to pass either on one side or the other of the wires of the grid 30 into one box 19 only. This is referred to in the art as a toggle action. The relative positions of the grid 30 to the boxes 19 and to the auxiliary grid is also shown in FIGURE 4.

It is advisable to suppress the beam 14 when the deflection voltages vary from one pair of values to another; this is achieved by obtaining a suppression potential, best applied to a control grid between the electron gun 13 and the deflection plates 15 and 16, when either or both deflection voltages are varying.

An application of the code translator according to the present invention where its advantages become apparent occurs when it is used with a symbol generating and display tube, as described in our co-pending application Serial No. 104,916 filed April 24, 1961, where an input code of six bits, representing any one of 64 characters, has to be translated into an output code of up to 35 bits to control the 7 x 5 matrix control element of the tube. In normal code translators several thousands of components are required to perform this task; for example, in the case of a core translator it would be necessary to have 64 cores with about 35 windings on some of the cores. On the other hand, in the present code translator the circuit consists of several thousands of pieces of wire 21 in properly assigned positions in the boxes 19.

It will be appreciated that there is also a fundamental advantage in the code translator according to the present invention as follows. In the normal diode translators, especially those of the resistance matrix type, there is some coupling between elements which should ideally be uncoupled electrically. In the electronic code translator tube according to the present invention, on the other hand, an electron beam 14 strikes various wires 21, which are not coupled in the absence of the beam 14. When the beam 14 strikes these wires 21, the wires 21 attain substantially the same signal potential, whereas in the absence of the beam the wires are isolated from each other, except for the direct capacitance between them, and this capacitance can be made very small.

The disclosure of specific embodiments is not intended to limit the scope of the present invention. Many changes may be made in the details set forth without departing from the spirit and scope of this invention, and these are intended to be within the meaning of the appended claims.

What is claimed is:

1. Apparatus for translating information in the form of a sequence of coded characters from an input code to an output code, comprising:

a cathode :ray tube including means to produce an electron beam and means to deflect said electron beam in response to an electrical input code signal, and

means in said tube to generate an output code signal when struck by the electron beam, said means including a plurality of target members having output code members,

said target means comprising output code members partly surrounded by electrically conductive openended box members arranged in rows and columns.

2. Apparatus according to claim .1 wherein said box members are rectangular in shape and are arranged in close juxtaposition with common walls to form a compact target aggregate.

3. Apparatus for translating information in the form of a sequence of coded characters from an input code to an output code, comprising:

a cathode ray tube including means to produce an electron beam and means to deflect said electron beam in response to an electrical input code signal, and

means responsive to said beam to generate an output code signal, said means including a plurality of electrically conductive open-ended box members each of which box members partly surrounds one or more output code wires extending thereinto and means to apply a pre-determined electrical potential to said box members.

4. Apparatus for translating information in the form of a sequence of coded characters from an input code to an output code, comprising:

means to produce an electron beam, 1

target means including a plurality of electrically conductive open end box members each having output code means comprising one or more conductive wires extending thereinto in signal generation relation to said electron beam,

means to deflect said electron beam into a predetermined one of said box members, and

means to concentrate the electron beam deflected into said one of said box members onto the output code means therein.

5. Apparatus for translating information in the form of a sequence of coded characters from an input code to an output code, comprising:

means to produce an electron beam,

means to direct said electron beam in response to a signal,

a plurality of target members comprising output code means extending into electrically conductive openended box members arranged in rows and columns, to generate an output signal when struck by the electron beam, and

deflecting means to prevent the electron beam from striking more than one of said target members at a time.

6. Apparatus according to claim 5 wherein said deflecting means comprises:

a grid member disposed in register with the walls of said box members and means to hold said grid at a predetermined switching potential to switch the electron beam into a particular box member.

5 6 7. An electronic code translator according to claim acter and associated with output code members, corre- 10, wherein said box members have a rectangular shape sponding to said character, are arranged to be struck seand are arranged in close juxtaposition with common riatim by an electron beam to generate appropriate outwalls to form a compact target in aggregate. put signals in said output code members, in terms of 8. An electronic code generator according to claim 5 5 said output code, in response to being struck by said with an additional limiting means comprising an auxelectron beam, said electrically responsive target memiliary grid and means to apply a predetermined electrical bers consisting of electrically conductive open-ended box potential thereto to limit the potential of said output code members arranged in rows and columns, each of said members. box members accommodating said output code members.

9. An electronic code generator according to claim 5 10 wherein said'outp-ut code members are electrically con- References (med y the Examine! nected to a clamping circuit including a diode whereby UNITED STATES PATENTS the potential of said output code members is limited to a predetermined value.

:10. An electronic code translator for translating information in the form of a sequence of coded characters 15 MAYNARD WILBUR Prlmary Exammer' from an input code to an output code, comprising a DARYL W. COOK, Examiner. cathode ray tube wherein a plurality of electrically re- K R STEVENS Assistant Examiner sponsive target members, each corresponding to a char- 3,115,623 12/1963 Beck et a1 340-347 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,264 ,638 August 2 1966 Arthur T, Starr It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, lines 5 and 10, for the claim reference numeral "5", each occurrence, read 7 Signed and sealed this 8th day of October 1968,

(SEAL) Attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 264 ,638 August 2 1966 Arthur Tr. Starr that error appears in the above numbered pat- It is hereby certified d that the said Letters Patent should read as ent requiring correction an corrected below.

Column 5 lines 5 and 10 for the claim reference numeral "5 each occurrence, read .7

Signed and sealed this 8th day of October 1968,

(SEAL) Attest:

EDWARD J BRENNER Commissioner of Patents Edward M. Fletcher, J r.

Attesting Officer 

1. APPARATUS FOR TRANSLATING INFORMATION IN THE FORM OF A SEQUENCE OF CODED CHARACTERS FROM AN INPUT CODE TO AN OUTPUT CODE, COMPRISING: A CATHODE RAY TUBE INCLUDING MEANS TO PRODUCE AN ELECTRON BEAM AND MEANS TO DEFLECT SAD ELECTRON BEAM IN RESPONSE TO AN ELECTRICAL INPUT CODE, SIGNAL, AND MEANS IN SAID TUBE TO GENERATE AN OUTPUT CODE SIGNAL WHEN STRUCK BY THE ELECTRON BEAM, SAID MEANS INCLUDING A PLURALITY OF TARGET MEMBERS HAVING OUTPUT CODE MEMBER, SAID TARGET MEANS COMPRISING OUTPUT CODE MEMBERS PARTLY SURROUNDED BY ELECTRICALLY CONDUCTIVE OPENENDED BOX MEMBERS ARRANGED IN ROWS AND COLUMNS. 